Privacy Policy

Last updated: 30 July 2026 · Applies to the Taller Ninja mobile and web app and taller.ninja

The short version: Taller Ninja is built privacy-first. By default, everything you enter stays on your own device. We show no ads, we use no tracking, and we never sell data. Creating an account is optional and only exists so you can back up and restore your own progress. There is one thing that does leave your device, and only if you use it: the questions you type into the Ninja Coach.

Who we are

Taller Ninja ("we") is published by RGI bv, Geenend 41/0001, 2470 Retie, Belgium (VAT BE0809911990). Contact: [email protected].

What data the app handles

Profile answers — age, height, parents' heights, the growth-formula answer (optional), sleep and sport habits. Used only to calculate your height estimate and personalise your plan.
Height log — the measurements you enter yourself.
Progress data — XP, streaks, belts, badges, completed exercises, reminder preferences.

By default all of this is stored only on your device. It is not sent to us or to anyone else. Two things can change that, and both are your choice: creating an account (backup) and asking the Ninja Coach a question. Both are described below.

Optional account (backup & sync)

If you choose to create an account — with your email address or by signing in with Google or Apple — your profile and progress data are additionally stored in our database (hosted by Supabase, in the EU) so you can restore them on a new device. We store your email address solely to operate your account. We do not use it for marketing without your explicit consent.

Ninja Coach (the AI chat)

The Ninja Coach answers questions about posture, sleep, food and movement. It needs an account, so it only works if you signed in — and if you never use it, nothing you type ever leaves your device.

What is sent: the question you type, plus the language you use, over an encrypted connection to our own server function. That function passes it to Anthropic, the provider of the AI model that writes the answer. Anthropic processes it on our behalf as a service provider, and does not use it to train models. They may retain the text briefly for their own abuse checks.
What we keep: not the questions and not the answers. We store only a counter of how many messages you sent today, linked to your account, to enforce the limit of 20 per day.
Unless you report an answer. Every coach answer has a "report this answer" link. If you use it, that one question and that one answer are sent to us and stored so a person can read them and fix what went wrong. It asks you to tap twice and tells you what it will send, because this is the only time coach text is kept. Reports are deleted with your account.
What is not sent: your name, your height, your measurements, your profile answers or your progress. The coach only receives what you type.

Please do not type things into the coach that you would rather not send anywhere — it does not need your personal details to answer a question about stretching. The coach gives general habit advice and never medical advice; it refuses off-topic questions and points you to a trusted adult where that is the better answer.

Crash reports

When the app crashes, it sends an anonymous crash report to Sentry (our error-reporting provider, EU servers) so we can find and fix the bug. A report contains the technical stack trace and basic device information — phone model, operating system, app version. It contains no personal data: no name, no email address, no height, no answers, and nothing you typed. We use these reports only to fix crashes, never to build a profile of you.

What we never do

No advertising and no ad networks.
No behavioural tracking or analytics profiles.
No selling or sharing of personal data with third parties.
No calorie counting or food diaries.

Children and teens

Taller Ninja is designed for teens. We deliberately collect the minimum data possible, everything is private by default, and accounts are optional. If you are under 16 (EU) or under 13 (US), ask a parent or guardian before creating an account. Parents can contact us at [email protected] to have a child's account and data deleted.

Deleting your data

On your device: Settings → "Delete all my data" removes everything instantly. Uninstalling the app does the same.
Account data: deleting your account in the app removes your backup, your coach message counter and the account itself from our database. You can also do it from this page, or email us and we will delete it within 30 days.

Notifications

Training and measurement reminders are local notifications, scheduled on your device. They involve no server and can be turned off in Settings or in your system settings.

Your rights (GDPR)

You have the right to access, correct, export and delete your personal data, and the right to complain to your data protection authority. For anything data-related, contact [email protected].

Not medical advice

Taller Ninja offers general lifestyle tips about exercise, posture, nutrition and sleep. It is not medical advice. Growth is largely determined by genetics — healthy habits help you reach your natural potential. Talk to a doctor if you have questions about your growth.

Changes

If we change this policy, we will update this page and the "last updated" date. Meaningful changes will be announced in the app.